Human Universe - Season 1 Episode 3 Are We Alone?
Overview: Brian Cox explores the ingredients needed for an intelligent civilisation to evolve in the universe - the need for a benign star, for a habitable planet, for life to spontaneously arise on such a planet, and the time required for intelligent life to evolve and build a civilisation. Brian weighs the evidence and arrives at his own provocative answer to the puzzle of our apparent solitude.